Technical Field
The instant disclosure relates to a piezoelectric ceramic speaker and a dual-band earphone having thereof.
Related Art
Please refer to FIG. 1, which provides a top view of a traditional piezoelectric ceramic speaker 100. The piezoelectric ceramic speaker 100 includes a conductive plate 110 and a ceramic plate 120. A plurality of sound delivering holes 111 is opened on the conductive plate 110. The ceramic plate 120 is installed to a surface of the conductive plate 110. The piezoelectric ceramic speaker 100 is assembled in a housing of an earphone and provided as a high-pitched speaker.
The ceramic plate 120 is designated to be of rectangular shape, so that the ceramic plate 120 can be manufactured by simple cutting process. However, the conductive plate 110 is of round shape. Therefore, in sound generation, the vibrations of the conductive plate 110 and the ceramic plate 120 are not uniform, parts of the vibrational energies of the conductive plate 110 and the ceramic plate 120 would be cancelled out by each other, and the sound distortion might occur easily.
Besides, since the conductive plate 110 and the ceramic plate 120 have different shapes, the difficulty in machine manufactory of the piezoelectric ceramic speakers 100 increases. Therefore, the piezoelectric ceramic speaker 100 has to be assembled manually. In addition, when forming the sound delivering holes 111, the sound delivering holes 111 might be formed on the conductive plate 110 with an offset from their predefined forming positions. Sometimes, forming the sound delivering holes 111 might make the conductive plate 110 uneven. Accordingly, the yield rate of the piezoelectric ceramic speaker 110 is reduced and it is hard to mass production by automatic machines.